This renewal application is a continuation of our studies designed to described the molecular mechanisms of tachykinin peptide biogenesis, axonal transport and turnover in the central nervous system (CNS) of the rat. The tachykinin family of peptides are neurotransmitter candidates in many neuronal systems and include Substance P (SP), Neurokinin A (NKA) and Neurokinin B (NKB). We have recently documented the existence of one rat preprotachykinin gen and three mRNAs derived from it that encode SP and NKA, and have further evidence of another distinct gene responsible for NKB production. We shall continue the molecular cloning of the genes, and mRNAs encoding these peptides to deduce their pathway of biogenesis. Analysis of the putative gene regulatory regions will allow for an analysis of tissue-specific expression of the genes and the mRNA primary structures will allow deduction of the precursor proteins encoding the tachykinins. The intracellular location and precise biochemical nature of the preprotachykinin processing events will be examined in cell-free translation systems, in large dense core secretory vesicles isolated from CNS regions, in selected cell lines infected with recombinant vaccinia vectors, and in discrete CNS projections in vivo. The regulation of tachykinin peptide biosynthesis and turnover during development and as a consequence of neurotransmitter input and gonadal steroid action will also be investigated in the basal ganglia, hypothalamic- anterior pituitary axis and ventral medulla-sympathetic preganglionic neuronal system. These studies will provide a basis for investigating whether aberrations in the biosynthesis or processing in peptidergic neurons are responsible for, or associated with, neurodegenerative and psychiatric disorders in which CNS peptides are implicated. As such, these investigations will provide a better understanding of basal ganglia SP/NKA neuron and their reported relationship to the Parkinson's disease and Huntington's chorea.